1. Field of Invention
This invention relates to fluid cleaning systems. Specifically, the present invention relates to devices for cleaning or recycling fluid, such as engine oil.
2. Description of the Related Art
Oil is a lubricant in a variety of applications ranging from electric generators to printing presses to automobiles. Such applications require clean oil with minimal liquid, gas, and solid contaminants.
Typical engine oil contains a variety of solid, gas, and liquid contaminants. Engine oil is contaminated by gases from engine cylinder blow-by, by solids from engine component wear, and by liquids from coolant leaks and condensed blow-by gas. Liquids combine with sulfur and other compounds from cylinder blow-by, creating corrosive acids, such as sulfuric acid. These contaminants corrode engine parts and deplete special minerals and detergents added to help maintain important oil properties, including lubricity and viscosity.
To reduce problems associated with oil contamination, full-flow filters were developed. All oil circulating around an engine equipped with a full-flow filter is directed through the filter or filter housing. High flow requirements limit the ability of conventional full-flow filters to remove very small solid contaminants. Large particles of twenty microns or larger often pass through such filters and contribute to engine wear. In addition, conventional full-flow filters are ineffective at removing liquid and gaseous contaminants from the oil.
To remove both solid and liquid contaminants from engine oil, mobile, i.e., on-board oil refining systems were developed. The systems continually remove, clean, and replace small amounts of oil from the engine as the engine operates. The systems include a special evaporation compartment that attaches to a by-pass filter. The evaporation compartment attempts to remove both gaseous and liquid contaminants from the oil, and the filter removes solid contaminants as small as one micron in diameter. Such small particles are often smaller than engine tolerances and do not contribute to engine wear. These oil-refining systems may obviate the need for interval oil changes but require interval filter changes.
The systems require a large evaporation compartment and an expensive electric heating element or an engine exhaust heater. The heating element or exhaust heater increases the risk of the systems exploding due to gas ignition. To reduce explosion danger, the evaporation compartments are constructed of strong, thick, and heavy metal, yielding expensive and bulky evaporation compartments.
The large size of the systems limits installation to large trucks and automobiles with ample space. Installation on most modern automobiles is difficult and expensive due to limited space. In addition, the electrical connections or exhaust gas conduits required for the electric heating elements or exhaust heaters, respectively, complicate installation and decrease the reliability of the systems. Public acceptance of the systems has been minimal because of these problems.
A newer system, lacking a heating element, is disclosed in U.S. Pat. No. 5,824,211 to Lowry. Unfortunately, the system disclosed in Lowry has several disadvantages. In particular, Lowry discloses a system having a tubular evaporation surface surrounded by a filter. Oil passes through the filter and onto the surface at several linearly distributed holes near the top of the surface. Lowry surmises that by placing holes at the top of the surface only, oil will have a further travel distance down the evaporation surface, thereby evaporating more volatile contaminants from the oil. This however, does not work as anticipated by Lowry, since the overall rate of evaporation of contaminants from the oil is based on the surface area of the exposed contaminated oil and not the travel distance of a particular portion of the oil. The linearly distributed holes promote channeling when the system is slightly tilted. Channeling of the fluid as it flows down the evaporation surface significantly reduces effective evaporation surface area. Furthermore, Lowry includes a vent, an oil drain, and an oil sample bore in a confined space at the bottom of the evaporation chamber. By positioning the vent in the bottom of the evaporation chamber, any contaminant gases in the evaporation chamber must overcome the buoyancy force of the vapors, which cause the vapors to rise, to evacuate out the vent. This requires significant vapor pressure, which is often not present due to the lack of a heater element. Furthermore, positioning the vent in the bottom of the evaporation chamber next to the oil drain forces undesirable space constraints on the size of the vent and the size of the oil drain. This necessitates a relatively narrow, restrictive vent, which further inhibits volatile contaminant circulation out of the system. The size of the drain is also compromised. This increases the likelihood of oil backing up in the system, covering the evaporation surface (thereby rendering it further ineffective) and flowing out the vent, which lacks a check valve. The design of the vent is also undesirable, as it includes a bend that further restricts the flow of gaseous contaminants from the system.
Hence, a need exists in the art for a safe, space-efficient and cost-effective mobile fluid recycling system that efficiently and effectively removes both solid and liquid contaminants from fluid, such as oil, without requiring a heater element. There is a further need for a system that may be easily installed on modern automobiles, which maximizes gaseous contaminant circulation out of the system.